I tune my NA setup with Sensed MAP enabled and the threshold at 0. I also disable baro learn, etc.
Combining this with full open loop tuning has yielded some nice improvements in drivability.
My cam isn't huge (222/230 112 LSA), but I can achieve a VERY smooth idle while in gear...... 800 idle... no lope... no surge. Awesome street manners. Could never do it with closed loop and sensed MAP disabled.
I also limit minimum MAP to 20 KPA.
It can be done though with much upside, mostly avoiding fouled plugs, better mpg, and better transitional fueling. I have tuned a 240/255 114+2 cam with a Kenne Bell 3.6 on top of a 448 aluminum motor, closed loop, sense map enabled, idles at 900 smooth as glass. FWIW no lope isn't really a sign of a good tune, usually that means you're running on the rich side or timing is too low. a 112 lsa cam with that duration should def have some chop at 800rpms.Originally Posted by kenandjenn4551
Min map should correspond to the sensor not some desired tuning threshold. The sensor will still read below that threshold but the ECU will stop caring for fueling and timing. Good you disable baro learn because that would give it fits.
Dredging this back up again.
So the TMAP multiplier (44395 in my file) airflow>general>map estimation looks to be the table that allows for the calculated or estimated map based on rpm and mass airflow - the mass airflow parameter looks like it comes from (35035 in my file) airflow>electronic throttle>throttle body model, which comes from volts (throttle blade position).
What do you guys think of that?
Last edited by spoolboy; 08-02-2019 at 11:39 AM.
Bit of a grave dig.
With sensed MAP enabled I've noticed that calculated MAP = sensed MAP but only up until the sensed MAP approaches the baro pressure (or some threshold very close to baro).
Once the PR > 1.0 (boost) the sensed MAP reads as expected but the calculated MAP remains somewhat pinned. Somewhat pinned as it's value still changes slightly, seems to be getting its value from elsewhere. It never rises above the baro or this threshold pressure though.
Now for the weirdness....
The aircharge is proportional to the sensed MAP regardless of the PR (as to be expected).
The total airflow also seems to follow this logical trend, however once the sensed MAP approaches baro and the calculated MAP gets pinned, it starts to drop significantly and has some very weird behavior (circled in red below). This is obviously not correct.
AirchargeVsAirflow.JPG
The throttle blade remains open here so this airflow parameter does not seem to have anything to do with the airflow in the ETC tables. It must be getting calculated from somewhere.
The implication here (and how I actually found this odd behaviour) is that the ECT/IAT blend tables to estimate the actual manifold air temp are driven by this total airflow parameter. Here you want the MAT more biased to the hotter ECT values at low airflows and the cooler IAT values at high flows. But with this airflow parameter not being calculated properly and actually dropping on boost, the MAT gets more biased to the ECT, increases, and actually leans out the fueling due to the SD model. Definitely not what you want!
Now even though the TMAP multiplier table has airflow on its axis, I'm wondering if its got anything to do with the calculated MAP and the calculation of the total airflow parameter?
The TMAP values supplied with my original DS 3.6L Sprintex tune are exactly the same as stock. The values never exceed 1. Could this be the reason why the calculated MAP never rises above ~100 kPa and could possibly explain the bizarre lowered total airflow values on boost?
Am I missing anything here? Thoughts?
Whats more important is where your actual IAT sensor is located, that will determine how much of the calculated temps you have to deal with. On most whipple, KB, and procharger setups, its located post compressor so its reading air temps after air is compressed. In these cases, you dont need any MAT calcs layered on top of your IAT readout, you just want the reading right off the sensor for tuning purposes. The MAT mappings are for when the sensor is located in the cold air intake on a NA setup and you want to map those values to a temp inside the intake manifold, which you no longer have to do.
You are 100% correct on all accounts regarding the MAT readings.
Unfortunately I?m dealing with the worst setup in which the IAT is placed pre-compressor as delivered by Sprintex.
So I'm having to do a bit of fudgery here with the MAT blend tables. Hence the question about the bizarre reduced total airflow values on boost as this trends to a significant leaning out of the AF.
Off boost everything seems fine and the airflow values seem logical and realistic so what causes them to drop once the PR>1.0?
It seems to be related to the calculated MAP becoming pinned under 100kPa or could this just be coincidence?
post a copy of your tune? you might need HPT to add a few missing parameters, you should be able to control the total airflow calc, something is amiss in your tune.
Thanks for the feedback 06300CSRT8. I've attached my current tune.
I stumbled across one of your old threads where you were calculating the total airflow: https://forum.hptuners.com/showthrea...ue-Correlation
Going through that it seems bizarre that my total airflows would drop on boost.
I just found it interesting that the total airflow starts to drop and have some odd values at the same point where the calculated MAP differs from the sensed MAP. Coincidence maybe?
02-05-20.hpt
After going though some previous threads as well as page 1 here, I noticed a bit of talk about a "Sensed MAP PR Threshold" parameter. This seems to have a factory default of 0.96.
This PR threshold value seems to correlate with my messed up total airflow values. Virtually every time my PR is greater 0.96, my total airflow parameter seems to drop significantly.
Here's another data log with a reference line at PR=0.96 which shows the total airflow dropping significantly once the PR is above 0.96. It seems rather convincing.
AirflowIssues.JPG
Unfortunately I don't have access to this parameter on the 3.6 Pentastar yet.
On a side note, if I remember correctly, in one of the pictures in the tuning school course book the PR threshold was set to zero when sensed map was enabled. I tried setting it that way and there was a significant off idle stumble when the pedal was applied.
While waiting for HPT to reply to my request I tried disabling "Sensed MAP".
Doing this seemed to give realistic total airflow numbers once the PR rose above ~0.96 and into boost. No bizarre drops as previously experienced, allowing my MAT blend table to work as intended.
AirflowSensedMAPDisabled.JPG
I did find that "Fine Tune" for the barometric pressure must also be disabled once sensed MAP is disabled otherwise the baro pressure will start creeping up. This does not occur with sensed MAP enabled. Baro "Learning" was disabled in both cases.
With sensed MAP disabled, calc MAP leads the sensed MAP value by ~3-5kPA on fast throttle transients (it responds faster) and gives values a few kPa lower than my minimum MAP sensor offset (20kPA). Calc MAP now saturates at ~5kPA below baro, slightly lower than before.
Besides these differences the two are virtually identical in value during steady-state (within ~1 kPA) but not 100% exactly the same as they were with sensed MAP enabled.
Disabling sensed MAP did not make any noticeable difference to my fuel trims under steady-state conditions, even on boost. This now makes me wonder what actual MAP value the code is using on boost in the SD equations.
I wonder if setting this PR threshold to zero is doing the exact same thing as disabling sensed MAP?
With sensed MAP disabled I did notice rougher off idle behaviour, which coincided with much larger A/F swings on throttle transients.
Well it looks like it back to the drawing boards...
Everything was going fine until it tripped a P2173 code and went into limp. Looks like this seems to be caused by disabling the sensed MAP according to this thread https://forum.hptuners.com/showthread.php?59236-P2173
This is going to be a tricky problem to overcome as enabling sensed MAP leads to strange airflow numbers that drop on boost. This really messes with the MAT blend table that I need to use due to the pre SC IAT sensor in the Sprintex setup.
Are you getting a buck in the car when you?re doing this? If you look at the electronica throttle position versus the pedal position are you seeing the electronica throttle clothes while the pedal still matted? Does it seem to do it multiple times if you stay in the throttle
The vehicle didnt buck it just lost a lot of power and sat with a high idle. Throttle body opening was severely limited when it tripped the code. I only ever once experienced odd throttle oscillation behavior which I managed to solve by doing a throttle relearn.
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